Sadly aviation is just one example of Brexit bringing about wasteful pointless bureaucracy and costs for British versions of things that already work perfectly well. Also as we are pretty much completely insignificant as a country who except Uk based entities is going to bother with compliance with any special Uk regulations.
This was demonstrated by UK banks who found that after Brexit they had to have 20 odd licences all across the Eu rather than one Eu licence and many just walked away from European operations.
Mind you if we kick air O Leary out of the Uk that might help prop up BA and easy who are sure as heck going to need it.